Some doc on file generation

python/dune/perftool/file.py

 """ Manages the generation of C++ header files """
 
-from dune.perftool.generation import retrieve_cache_items
 
 def generate_file(filename, tag, content, headerguard=True):
     """
@@ -8,9 +7,18 @@ def generate_file(filename, tag, content, headerguard=True):
 
     Arguments:
     ----------
+    filename : str
+        The filename to write the generated code to.
+    tag: str
+        The tag, that all entries related to this file in the cache have.
+    content: list
+        A list of Generables to put into the file.
 
     Keyword Arguments:
     ------------------
+    headerguard : bool
+        Whether a double inclusion protection header should be added to the file.
+        The name of the macro is mangled from the absolute path. Defaults to True.
     """
     with open(filename, 'w') as f:
         # Add a double inclusion protection header
@@ -19,6 +27,7 @@ def generate_file(filename, tag, content, headerguard=True):
             f.write("#ifndef {0}\n#define {0}\n\n".format(macro))
 
         # Add the includes from the cache
+        from dune.perftool.generation import retrieve_cache_items
         for inc in retrieve_cache_items((tag, 'include'), union=False):
             from cgen import Include
             assert isinstance(inc, Include)